Support sampling into non-contiguous arrays

This is currently silently broken, which is dangerous:
```julia
julia> randn!(local_rng(), view(X, :,2,:))
3×3 view(::Array{Float64, 3}, :, 2, :) with eltype Float64:
-0.601185 0.0 0.0
0.529745 0.0 0.0
-1.30729 0.0 0.0

julia> X
3×3×3 Array{Float64, 3}:
[:, :, 1] =
0.0 -0.601185 -0.662154
0.0 0.529745 1.66186
0.0 -1.30729 0.848472

[:, :, 2] =
0.891294 0.0 0.0
0.928313 0.0 0.0
-1.01618 0.0 0.0

[:, :, 3] =
0.0 0.0 0.0
0.0 0.0 0.0
0.0 0.0 0.0
```